Generator with multiple voltage regulators

ABSTRACT

A solid-state series regulator is disclosed which controls the output of one phase of a multiple output three-phase alternator, whose remaining two phases have their output controlled by a solid-state regulator which varies the current to a rotating field exciting the alternator. The alternator is preferably used to charge two standard batteries, the main battery being charged by the two cooperating phases of the alternator whose output is controlled by the regulator for the field, while the auxiliary battery is charged by the third separate phase regulated by the solid-state series regulator. The two batteries are connected in series and connected to loads requiring different voltages.

United States Patent 1 [111 3,710,226

Seike 1 Jan. 9, 1973 [54] GENERATOR WITH MULTIPLE VOLTAGE REGULATORS Primary Examiner-J. D. Miller [75] Inventor: Helmut K. Seike, Toledo, Ohio g ggz;; tgfiz; g

[73] Assignee: Eltra Corporation, Toledo, Ohio 22 Filed: March 25,1971 [571 ABSTRACT [211 App. NM 128,027 A solid-state series regulator is disclosed which controls the output of one phase of a multiple output three-phase alternator, whose remaining two phases have their output controlled by a solid-state regulator which varies the current to a rotatingfield exciting the lnt- "H021 alternaton The alternator is preferably used to charge [58] Field of Search ..320/59-6l 15' two standard batteries, the main battery being charged 322/28, 59, 94; 321/8 by the two cooperating phases of the alternator whose output is controlled by the regulator for the field,

I Reference? Cited while the auxiliary battery is charged by the third UNITEDSTATES PATENTS separate phase regulated by the solid-state series regulator. The two batteries are connected in series and 3,379,957 4/1968 Guglielmi ..3Z2/ 5 9 X connected to loads requiring different voltages. 3,176,212 3/1965 De Puy ..-....32l/8 3,538,421 11/1970 Young ..;....322/28 3 Claims, 3 Drawing Figures I2 VOLT Buss 36 L i 5. i K A/-: WW

PHASE I PHASE 2 GENERATOR WITH MULTIPLE VOLTAGE REGULATORS In application Ser. No. 90,899 filed Nov. 19, 1970 and assigned to the same assignee as the present case, a three-phase multiple-output alternator is disclosed and claimed, to which the present invention is applicable. The solid-state series regulator controls the output of a third separate phase which charges the auxiliary battery, which is series connected to the main battery of the system, the main battery being charged by the two remaining cooperating phases of the alternator, the output of which is regulated by a conventional solidstate regulator by controlling the exciting current in the field exciting the rotor of the alternator.

It is therefore a principal object of this invention to provide a solid-state series regulator controlling the output of a third separate phase of a multiple-output alternator whose main output from the two remaining cooperating phases is controlled in a conventional manner by a regulator controlling the field current to the rotating field member.

It is a further object of this invention to provide regulation to an auxiliary power consuming circuit for a multiple-output alternator wherein silicon-controlled rectifiers are used for both rectification and output control.

Other objects and advantages of this invention relating to the arrangement, operation and function of the related elements of the structure, to various details of construction, to combinations of parts and to economies of manufacture will be apparent to those skilled in the art upon consideration of the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIG. 1 is an elevational view partly in cross section showing an alternator incorporating the invention.

FIG. 2 is an elevational end view of the alternator, partly in section taken from the left end of FIG. 1.

FIG. 3 is a schematic diagram of connections of the preferred form of the invention.

Referring to the drawings, particularly to FIGS. 1 and 2, an alternator is shown having a laminated stator element in which power-producing coils l2 and 14 are mounted in its slots 16 in a conventional manner. It is to be understood that the power coils l2 and 14 may be connected together in various ways as will appear hereinafter, so that a single portion of a power coil may be mounted in a single slot or portions of two or even more coils may be so mounted, depending upon their function in the power circuits.

The stator element 10 is clamped between end heads 18 and 20 by conventional through-bolts 22, the heads being provided with conventional bearings in which is journalled drive shaft 24 protruding from one side of the alternator as shown in FIG. 1, where a conventional drive pulley or other driving member (not shown) may be attached, exteriorly of a cooling fan 26. The end heads 18 and 20 are provided with any suitable mountings lugs 28 whereby the alternator can be 1 speed engine of the vehicle.

End head 18 is provided with an output terminals 36 and a field terminal 38 which is in circuit with the field coil 34 mounted on the rotor 30 in the manner already described. Regulating means (not shown) of a conventional solid-state semi-conductor type may be mounted inside the alternator casing by bolt 40 cooperating with conventional heat sinks. The regulating means as is well known, controls the direct current to the field coil 34 in such a manner that the voltage appearing at the output terminals 36 is maintained within predetermined limits. A second output wire terminal 42 (FIG. 2) is also provided connected to the second power coil as will be described hereinafter. This output voltage is also regulated by a solid-state type static regulator which incorporates the invention, being mounted in encapsulated state in an external casing 44 mounted by lugs 46 on the outside of the end head 18 by bolts 48. Conductors 50, 52 and 53 extend from the casing 44 to the interior of the alternator to connect the regulator mounted therein to the alternator elements as will appear hereinafter. Terminal bolt 48 provides a negative ground for the alternator.

Referring to FIG. 3, which discloses a schematic diagram of connections of an alternator incorporating the invention, a pair of 12 volt batteries are shown ofwhich battery A is the main battery and battery B is the auxf iliary battery. The batteries A and B are connected in vehicle including ignition, lighting, radio, heater, etc.,

while the 24 volt buss may supply power to the starter motor of the automotive vehicle or other intermittent 24 volt loads. Various switches, circuit breakers, fuses and so forth that might be required on a particular vehicle have not been shown.

A representative alternator shown in FIG. 3 is a three-phase type, wherein coils 14 are connected as a two-phase winding, while the third phase has a center 7 tap, C, maintained on the stator as a separate winding.

mounted in conventional manner on a vehicle in a Phase I and phase 2 are connected to a full wave rectifier R consisting of six silicon rectifiers, the outputs of which are connected from negative ground to-positive 12 volts buss, (terminals 48 and 36 respectively) to supply the charging power for battery A and the main electrical system of the vehicle. The field winding 34 which magnetically excites all three phases is connected to the output of the rectifier R in a cooperative relation with the voltage regulator 56 via field terminal 38, whereby a controlled direct current is supplied to the field coil 34 to maintain the voltage of the output of phases 1 and 2 within predetermined limits.

' The generated AC voltage across the auxiliary output winding 12, of the alternator is a function of the magnetic field strength and the velocity of the field vwinding 34. This voltage varies in magnitude and frequency if the field excitation and speed vary. The excitation in turn is a function of the varying main load as the field-regulator 56, attempts to maintain a preset constant output voltage across terminals 36 and 48.

It is therefore necessary to regulate the rectified output voltage of winding 12 of phase 3 to prevent overcharging of the battery B. Since the. power demands of the 12V and 24V buss are independent of each other,

the regulation characteristics of the auxiliary output must be independent of the regulation characteristics of the field-regulator 56. A series regulator circuit 58 is shown for the auxiliary circuit which operates as folceeds the DC voltage of the auxiliary battery B. At AC output voltages below this DC level or at standstill of the alternator, the SCRs are reversed biased by battery B and therefore, turned off. This circuit is a gated fullwave rectifier operating in an ON-OFF switching mode.

If the battery B reaches the predetermined voltage level, the breakover voltage of the reference-zener diode CR is exceeded. Transistor Q will turn on, thus cutting off transistor 0,. This action removes the positive gate potential from both SCRs. They each will then reset as soon as their anode voltage drops below thebattery voltage.

, The cut-off condition will remain until the voltage of the auxiliary battery B decays'below the knee-voltage of the reference diode CR Decay of this voltage can be caused either bythe natural leakage current of the auxiliary battery or by a load placed across the +24V buss terminals 42 and 48. The SCRs 60 and 62, there fore, will again be turned on and supply charging current to Battery B.

The selection of the reference voltage of zener CR, in conjunction with the natural negative base-emitter temperature coefficient of transistor Q is such that a predetermined negative temperature slope of the regulated voltage, across terminals 54 and 42 is obtained. That is, the voltage cut-off level of the regulator decreases with increasing ambient temperature.

The diodes CR CR prevent the application of a reverse voltage to transistor 0,, which would occur because of the AC voltage produced by winding 12.

The system exhibits simplicity, low dissipation losses, and a desirable negative temperature-dependent regulation characteristics necessary for reliable battery charging. Due to its compactness, it can easily be physically mounted incontainer 44 or combined within the samepackage as the field regulatorcircuit 56.

The resistors-R, or R, can be made variable'for convenient adjustment of a chosen charging voltage cut-off level. The auxiliary battery B provides the gate'currents.

34 is fully energized by field regulator 56, because of high load demand across terminals 36 and 48 and at high speeds of the alternator, the current through resistor R would become very high causing high losses and would require a higher power handling capacity of transistor 0;. By using the battery as DC trigger in- 1 stead, this problem is avoided. Thermal safety cut-off switches can be incorporated as optional measures if desirable.

With these parameters for the alternator, the normal electrical power requirements from phases 1 and 2 for a vehicle may be supplied with a total output of 80 amperes at the charging voltage of battery A. If the state of charge of battery B is low, as much as 20 amperes may be generated in phase 3 at the voltage required to charge the battery, which will be subtracted from the output of phases 1 and 2, so that about amperes will be generated in these phases. This is due to the limited amount of magnetizing force generated by the field coil 34 which will be utilized for the magnetic excitation of all three phases. If phase 3 is not utilizing sufficient magnetizing force to generate its maximum output of 20 amperes, that remaining will automatically be available to generate output in phases 1 and 2 if required so as to increase their available power outputs. In this way, an automatic regulation of the division of power between main phases 1 and 2 and the auxiliary phase 3 is attained.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings since the invention is capable of being practiced and carried outin various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements of the prior art.

I claim:

1. In combination with an alternator driven by a variable speed power source in a vehicle having at least two batteries, said alternator having at least two' separate generating phases magnetically excited by a field coil, a a

regulator for supplying power to said field coil to maintain a predetermined voltage in one of the phases to supply a variable load including a first of said batteries,

a pair of coils connected in series in the second phase each having a capacity to create comparable AC volt.- ages for charging the second battery, a pair of alternately conducting silicon-controlled rectifiers having their cathodes connected to the ends of the series connected coils with their anodes connected to the negative side of the second battery, the centralconnected ends of the coils in circuitwith thepositive side of the batt ry, a voltage divider across the battery responsive to the voltage of the battery, a zener diode cooperating with the voltage divider to change its conductive state at a predetermined breakover voltage applied thereto by the battery through the voltage divider, and a pair of transistors controlled by the zener diode connected together to maintain opposite states of conduction, one of the transistors connected to the gates of the silicon-controlled rectifiers whereby a positive bias is applied to the gates when the battery voltage is below the predetermined voltage of the zener diode, the bias being removed from the gates when the predetermined voltage for breakover on the zener diode is exceeded causing a reversal of the states of conduction of the transistors, with the bias on the gates removed ter- 

1. In combination with an alternator driven by a variable speed power source in a vehicle having at least two batteries, said alternator having at least two separate generating phases magnetically excited by a field coil, a regulator for supplying power to said field coil to maintain a predetermined voltage in one of the phases to supply a variable load including a first of said batteries, a pair of coils connected in series in the second phase each having a capacity to create comparable AC voltages for charging the second battery, a pair of alternately conducting silicon-controlled rectifiers having their cathodes connected to the ends of the series connected coils with their anodes connected to the negative side of the second battery, the central connected ends of the coils in circuit with the positive side of the battery, a voltage divider across the battery responsive to the voltage of the battery, a zener diode cooperating with the voltage divider to change its conductive state at a predetermined breakover voltage applied thereto by the battery through the voltage divider, and a pair of transistors controlled by the zener diode connected together to maintain opposite states of conduction, one of the transistors connected to the gates of the silicon-controlled rectifiers whereby a positive bias is applied to the gates when the battery voltage is below the predetermined voltage of the zener diode, the bias being removed from the gates when the predetermined voltage for breakover on the zener diode is exceeded causing a reversal of the states of conduction of the transistors, with the bias on the gates removed terminating the conductive period of the silicon-controlled rectifiers at the next following opposing half cycle of the AC Output.
 2. The regulator defined in claim 1 further characterized by temperature compensation by the negative base-emitter temperature coefficient of the transistor cooperating with the zener diode.
 3. The regulator defined in claim 1 further characterized by utilizing variable resistors in the voltage divider to adjust the voltage charging level. 